1. Field of the Invention
The disclosure relates to a voltage regulator device and a control method thereof.
2. Description of the Related Art
In general, the power supply does not directly supply power to the center processing unit (CPU) in a computer system. The main reason is that the core voltage (Vcore) required by the CPU changes with the change of the load, thus the core voltage (Vcore) required by the CPU may vary. However, a general power supply cannot react directly to a sudden voltage change. Therefore, a voltage regulator module (VRM) is conducted on the motherboard for supplying power to the CPU. The voltage regulator module can receive feedback signals from the CPU to adjust the voltage according to the feedback signal, and the voltage would not change suddenly because of a sudden change of current to impact the operation of the CPU.
In generally condition, when the output current of the voltage regulator module is above 20 A (the CPU overloads), the voltage regulator module operates at the continuous current mode (CCM), therefore, the output current waveform is continuous triangular waves. When the load current supplied to the CPU instantaneously reduces to less than half of the output current, in which the load is changed from heavy load to light load, the voltage regulator module generates a negative current (the direction of the negative current is opposite to the original current), the negative current causes additional loss and reduces the overall efficiency. In addition, there is a time delay for the negative current rising from the negative lowest point to 0 amps, the time delay makes the voltage regulator module spend more response time to provide positive current to the CPU and thus slows the reaction speed of the voltage regulator module down.